ลักษณะดินและศักยภาพการกักเก็บคาร์บอนและน้ำในป่าชุมชนที่เป็นป่าเต็งรังของหมู่บ้านท่าสะแล อำเภอฝาง จังหวัดเชียงใหม่

Abstract

Soil characteristics and carbon-water storage potential in the dry dipterocarp community forest of Tha Sa Lae village were studied for the purpose of obtaining features and condition in of the dry dipterocarp forest as well as its environmental influences which implied to ecological sustainability. As for, studing management and utilization of community forest provided useful information about a sustainable forest management with people partcipation. Plant community survey used twenty sampling plots, each of size 40x40 m2 arranged by a random sampling. Plant data in these plots were obtained by measuring stem girths at 1.3 meters above ground and heights of all trees with height over 1.5 meters and use 2 subplot, each of size 5x5 meters, at the center of big plots for studying ground-covered species. Plant quantitative features, species diversity biomass amounts, carbon, nutrient and water storages in the biomass were calculated. Tree plots were selected for soil study, three pedons with 1.5 metters width and variable depths depended on soil depths. Soil sampling with three replications were taken along the depths with composite samples for analyzing physical and chemical properties, amounts of carbon, nutrients and water storage in the soils. The amounts of carbon and nutrients losses from collecting D.tuberculatus leaves for sale were estimated.

A total of 50 species in 45 genera and 28 families was found in the plant community with an averaged density of 302.70 trees/rai, and the dominant tree species was D. tuberculatus, It had also the highest importance value index (IVI), 52.05% of all species, followed by Shorea obtusa, Gluta usitata, Aporosa villosa and Gardenia obtusifolia, respectively. Species diversity indexes (SWI) and forest condition index (FCI) were calculated to be 1.91 and 1.55, respectively. Existing seedling and ground-covered species were 53 species in 48 genera, 28 families, and the most common seedlings was D. tuberculatus. The ground-covered species were Lygodium flexuosum, Indigofera sootepensis, Leea indica, Chromolaena odorata and Setaria verticillata, etc. Soil in the forest had 80-120 cm in depth and might be classified to Order Ultisols or Alfisols because the base saturation was not analyzed. The developing soil profiles were A-BA-Bt1-Bt2-Bt3. Bulk density in surface soils was moderately low and moderately low to moderately high in subsoils. The surface soils had coarse texture including sand and loamy sand whereas subsoils were coarse texturedto fine textured: loamy sand, sandy loam, sandy clay loam, sandy clay and clay. Small gravel contents were observed in surface soils, and greatly varied in subsoils. The surface soils had strongly acid to moderately acid in contrast to very strongly acid to neutral in subsoils. Contents of organic metter and carbon were moderately medium to high in surface soils and lower in subsoils. Total nitrogen was very low thoughout the peofiles. Available phosphorus was medium to very low in the surface and lower in subsoils. Extractable potassium and magnesium varied from very low to very high throughout soil profies while extractable calcium were very low. The amounts of carbon (C), nitrogen (N), phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg) lost by removing D. tuberculatus leaves were 99,114.23; 1,813.48; 154.34; 1,618.14; 99,548.31 and 1,885.82 kg, respectively.

Total plant biomass in the forest was estimated at 75,650.13 kg/ha, and it could store amounts of carbon (C), nitrogen (N), phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg) in the biomass as 37,377.19; 347.58;40.43; 172.07; 673.58 and 103.23 kg/ha whereas those amounts in there soils were in the order of 10,875.98; 625.93; 31.43; 2,007.16; 2,061.37 and 11,294.92 kg/ha.

Therefore, the total ecosystem amounts were 48,253.17; 973.51; 71.86; 2,179.24; 2,734.95 and 11,398.15 kg/ha, respectively. The mean maximum capacity of water storage in dipterocarp forest was 2,746.85 m3 /ha. This included the amounts of water stored in plant biomass as 82.97 m3 /ha and the amount in soil at 2,663.88 m3/ha. The majority amount of water storage in the ecosystem was in soil 96.98 % of the total water storage.

Management and utilization of the community forest were practiced by setting rules. Villagers and neighboring communities collected forest products under the agreement. Establishment of the “Forest Protection Volunteer People's Committee of D.tuberculatus Leaves”. It is a unitedness of network communities for conservation and surveillance of the forest implied to their consciousness. Currently, a direct forest benefits was practiced including tree cutting for making houses, agricultural equipments and firewoods. There are seasonal forest producet collection such as mushrooms, vegetables, crickets and ant eggs. The most important product was providing income was fallen D. tuberculatus leaves as weaving them into the product (called Pai) for sale. The indirect forest benefit is the place for learning of natural resources, managing and utilizing commnity forest for interested people.